Graphical user interfaces such as the Microsoft Windows' operating environment comprise the most popular operating environment for the world's best selling applications software. Such environments are typically preferred because of ease of use, uniformity of user interface, high quality display, as well as other reasons. However, such user environments were designed for use with workstations and microcomputers such as personal computers. Such workstations and microcomputers, while flexible, present difficulties with security, reliability, ease of administration, and value. While data terminals are known to offer the advantages of improved security and ease of administration relative to microcomputers, usually at lower cost, terminals have generally been unable to provide compatibility with the most popular graphical user interfaces. Terminals operating in the X environment can provide some graphical interface capabilities operating under UNIX, but typically are expensive, require extensive memory, and offer little compatibility with the most popular Windows environments.
Another option known in the prior art is diskless PCs. However, diskless PCs offer several deficiencies. In most instances, diskless PCs operating in a client server environment display application program information by downloading the application from the server and executing the application locally. This requires the diskless PC to have whatever processing power is required for each application it attempts to execute. In today's environment, this can require eight or more megabytes of memory, per application, a powerful processor, and so on making a diskless PC expensive. In addition, diskless PCs offer limited security and can require extensive administration.
The Windows NT operating system provides a robust network client/server environment, while at the same time offering compatibility at the applications program level with the popular Windows environment. However, the NT operating system was written for PC clients, and not terminals. As a result, NT clients are generally required to be robust and, as a result, expensive. In addition, Windows NT was written for the client/server environment, and not the multi-user environment. The Multi-User NT operating system offered by Citrix Systems, Inc., modifies the Windows NT operating system by extending it to operate in a multiuser environment, although the prior art application for Multi-User NT has been PCs clients as opposed to terminals.
There has therefore been a need for a terminal that is relatively inexpensive, reliable, easy to administer, secure and capable of displaying application program information within a multiuser Windows operating environment.